The country crooner couldn't help but marvel over his beautiful wife, who celebrated her 51st birthday on Friday. Sharing a handful of pictures of Hill as a child, a throwback of the two, and of her with their kids, McGraw, 51, wrote about how he knew that his lady was the "love of my life forever."
"From the first time we met, I knew that she was the love of my life forever," McGraw began his tender note. "No matter the ups and downs, the happy and sad or the good and bad. She’s so special and so loved by us. Happy birthday my love."
"When I wake up next to you in our 80’s, I’ll smile at the life we’ve built," he sweetly concluded.
The couple has been married since 1996, and are parents to three daughters: Gracie, 21, Maggie, 20, and Audrey, 16.
Last year, McGraw and Hill released their first joint album and have been touring together ever since. ET caught up with the lovebirds before their Soul2Soul World Tour, where McGraw gushed about getting to see his wife perform every night, admitting he's still in awe of her.
"For me, it's hearing her sing every night -- that's the best part about [the tour]," McGraw said. "Because she's not out there singing much... To see her up on stage, having a great time and just belting it out? I mean, I always say it: when I'm on stage with her, it's like NASCAR trying to keep up with an Indy car. She's just that good. So, to watch her sing and see what she does is pretty inspiring."
The perfect pair also opened up about the secret to their 20+ year marriage.